Chapter 3- Synapses Flashcards
synapse
specialized gaps/ junctions between neurons used to communicate by transmitting chemicals
reflexes
automatic muscular response to stimuli
reflex arc
the circuit from sensory neurons to muscle response (the speed of conduction)
temporal summation
repeated stimuli within a brief time having a cumulative effect
presynaptic neuron
the neuron that delivers that synaptic transmission
postsynaptic neuron
the neuron that receives the message
excitatory postsynaptic potential
a graded depolarization that occurs when Na+ ions enter the postsynaptic neuron
spatial summation
synaptic input from several locations exerting a cumulative effect and trigger a nerve impulse
inhibitory postsynaptic potential
the temporary hyperpoalrization of a membrane (occurs when K+ leaves the cell or Cl- enters the cell after it is stimulated)
spontaneous firing rate
the ability to produce action potentials without synaptic input (esps increase above the rate; isps decrease below the rate)
neurotransmitters
chemicals that travel across the synapse and communicate between neurons )released by one neuron and affect another)
amino acids
acids containing an amine group (NH2)
neuropeptides
chains of amino acids (polypeptide - protein)
acetylcholine
a chemical similiar to amino acid replaced by a N(CH3)3 group
monoamines
neurotransmitters containing an amine group formed by a metabolic change of amino acid
cathecholamines
compounds containing a catechol and an amine group (dopamine, epinephrine, norepinephrine)
tryptophan
precursor for serotonin
vesicles
tiny spherical packets that store high concentrations of neurotransmitters near the presynaptic (held for release)
MAO (monamine oxidase)
a chemical that breaks down excess levels of some neurotransmitters into inactive chemicals
exocytosis
(neurotransmitter release) the excretion of the neurotransmitter from the presynaptic terminal into the synaptic cleft
triggered by an action potential arriving from the axon
ionotropic effect
when a neurotransmitter attaches to receptors and immediately opens ion channels
transmitter gated/ ligand gated channels
channels of sodium and potassium along an axon , controlled by a neurotransmitter
metabotropic effects
when neurotransmitters attach to a receptor and initiates a sequence of slower and longer lasting metabolic reactions
G-proteins
a protein couple to the energy-storing molecule guanosine phosphate
second messenger
a chemical that communicates to areas within the cell
neuropeptides (neuromodulators)
neurotransmitters that alter the effects of a neurotransmitter
neurogliaform cell
a neuron shaped like a glia cell that releases huge amount of GABA all at once, producing widespread inhibition
hormone
a chemical secreted by a gland or other cells and is transported to other organs by the blood whose activity it influences
endocrine glands
responsible for the production of hormones
protein hormones & peptide bonds
composed of chains of amino acids and attach to membrane receptors where they activate second messenger systems
pituitary gland
attached to the hypothalamus and consists of two glands
anterior pituitary
composed of glandular tissue and synthesizes 6 hormones
posterior pituitary
composed of neural tissue and can be considered an extension of the hypothalamus
oxytocin & vasopressin
antidiurect hormone released from the posterior pituitary synthesized in the hypothalamus
reuptake
when the presynaptic neuron takes up most of the neurotransmitter molecules intact and reuses them through transporters
acetylcholinesterase (AChe)
enzymes that breaks down into acetylcholine (reabsorbed and recycled)
COMT
enzymes that convert the excess into inactive chemicals
autoreceptors
receptors that detect the amount of transmitter released and inhibit further synthesis and release
antagonist
a drug that blocks a neurotransmitter
agonist
a drug that increases a neurotransmitters effects
gap junction
the membrane of one neuron coming into direct contact with another in an electrical synapse
affinity
how strongly the drug attaches to the receptor
efficacy
the tendency of the drug to activate a receptor
stimulant drugs
produce excitement, alertness, elevated mood, decreased, motor activity (addictive)
amphetamine
increases dopamine release from presynaptic terminals by reversing the direction of the dopamine transporter
cocaine
blocks the reuptake of catecholamines and serotonin at the synapse
methylphenidate
blocks the reuptake of dopamine at presynaptic terminals
nicotine
stimulates one type of acetylcholine receptor known as the nicotinic receptor
opiate drugs
those that are derived from the opium poppy
endorphins
peptides that the brain produces (reinforcing effects)
tetrahydocannabinol (THC)
cannabinoids
active ingredient in marijuana
anandamide/ 2-AG
brain chemicals that bind to cannabinoid receptors
hallucinogenic drugs
drugs that distort perception
alcoholism/ alcohol dependence
the continued use of alcohol despite medical or social harm
alcohol
stimulant that enhances response by the GABA receptor, blocks glutamate receptors, and increases dopamine activity
tolerance
decreased effect of a drug following repeated use
acetaldehyde
a poisonous substance created when alcohol is metabolized in the liver
antabuse (disulfiram)
a drug that blocks the effects if the enzyme acetaldehyde dehydrogenase by binding to its copper ion
